Double end operable axial switch



y May 10, 1966 J. E. JENNINGS DOUBLE END OPERABLE AXIAL SWITCH Filed April 26, 1963 m m I. 1 2.

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United States Patent 3,250,880 DOUBLE END OPERABLE AXIAL SWITCH Jo Emmett Jennings, La Selva Beach, Calif, assiguor to Jennings Radio Manufacturing Corporation, San Jose, Calif., a corporation of Delaware Filed Apr. 26, 1963, Ser. No. 275,811

- 6 Claims. (Cl. 200-144) The invention relates to electric switches; and particularly to a hermetically sealed power switch.

As demand for higher power capabilities in electric switches has increased, there has been a tendency to make switch structures more massive. self, however, introduces problems in the manufacture and operation of electric switches such as excessive weight,

inertial forces of massive mobile contacts.

excessive cost, and excessive power to overcome the It is accordingly one of the principal objects of the present invention to provide a power switch structure having high current carrying capacity while being relatively light in weight.

The demand for higher power has also resulted in efforts to provide multiple-break switch assemblies through the mechanical interconnection of switch structures designed to operate individually. It is therefore another object of the invention to provide a power switch structure suitable for single-switch operation or for multipleswitch assembly and operation in Which individual switches are interconnected in tandem so as to operate simultaneously.

Power switch devices have not heretofore been designed to etficiently accommodate direct current, loW frequency alternating current or radio frequency current.

For instance, it is well known that at radio frequencies,

icurrent travels on or near the surfaces of conductors,

and that the great mass of material in the center of solid conductors is largely useless insofar as conduction of current is concerned. Nevertheless, solid conductor switches have continued to be utilized in radio frequency applications where it would have been more appropriate to utilize a switch structure specifically designed for radio frequency operation. It is therefore a still further object of the invention to provide a power switch device having broad contact surfaces for the conduction of radio frequency current.

In vacuum switches having large diameter contacts enclosed within a hermetically sealed envelope it is difiicult to support the mobile'contact so as to assure proper and continuous alignment of the mobile contact with uum switch structure in which the contacts are arranged and supported so as to prevent such relative lateral displacement.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be apparent from the following description and the drawing. It is to be understood however that the invention is not limited by the said description and drawing but may be embodied in various forms within the scope of the appended claims.

Broadly considered, the switch of the invention comprises a tubular dielectric envelope portion closed at each opposite end by a relatively heavy metallic end plate hermetically sealed to the associated end of the dielectric envelope portion. Mounted on each end plate and extending into the tubular dielectric portion is a tubular current-carrying reentrant portion of the en Massiveness it-- mobile contact upon the fixed contact.

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velope terminating in a transverse wall section spaced from the corresponding transverse wall section supported on the opposite end plate. Each of the tubular conductive reentrant portions includese an expansible and contractable wall section to permit axial movement of the associated transverse wall section which closes the inner end of the expansible wall section. An annular movable contact mounted on one of the transverse wall sections is adapted to make and break contact with a tubular fixed contact rigidly fixed on an end plate. Mounted on each end plate is a centrally disposed bearing structure slidably supporting the outer end portion of an actuator shaft which at its outer end is provided with means for interconnection with a shaft as from another switch arranged in tandem relation, or other actuating shaft as from a solenoid. The inner end of each actuator shaft is connected to the associated transverse wall section which co-operates with the expansible wall section to hermetically seal this reentrant portion of the envelope. Atmospheric pressure; working on the interior of the reentrant portions thus tends to close the Brazed to one of the transverse wall sections within the envelope is one end of dielectric actuator rod extension, the other end of which is fixed to the opposite and axially spaced transverse wall section so that in effect a continuous rod extends concentrically through the envelope. The dielectric intermediate portion functions to electrically insulate one transverse wall section from the other while preventing lateral displacement of the mobile contact during operation of the switch. To prevent condensation of vaporized contact metal on adjacent dielectric portion of the device, -a shield structure is provided arranged to provide an annular substantially metal-lined contact chamber within which vaporized contact metal is trapped to effect its condensation.

' Referring to the drawing:

The figure is a vertical cross sectional view taken through the central axis of the switch. The tandem 'the end plate 3 being associated for purposes of this description with the mobile end of the switch, and the end plate 4 being associated with the fixed end of the switch. Each end plate is hermetically and flexibly united to the associated end of the tubular ceramic, which has been appropriately metallized, by a seal structure 6 constituting a cylindrical metallic flange 7 brazed to the end plate, and an integral radially extending flange 8 brazed to the metallized end of the ceramic. A ceramic back-up ring 9 is brazed to the opposite side of the flange 8 from tubular ceramic 2 and slidably abuts the associated end plate in order to accommodate differences in thermal expansion and contraction between the end plate and tubular ceramic. I

Concentrically mounted on end plate 3 and extending into the envelope is a tubular conductive member 12 having on its inner end an expansible extension 13, formed preferably from a metallic bellow. The end of the bellow remote from the tubular conductive member 12 is hermetically closed by a transverse wall section 14, which functions also as a movable support for a tubular mobile contact member 16 having an annular contact surface 17 formed of the same or a different material, such as tungsten. The transverse wall section 14, together with the bellow 13 and tubular conductive member 12 thus form verse wall section 14 also serves'as a mounting base or support for the inner end 18 of an actuator shaft 19, which is slidably disposed in a dielectric slide bearing 20 detachably mounted in a central aperture formed in end plate 3. The bearing ,20 is conveniently secured to the end plate 3 as by threads 21. As shown in the drawing, the actuator shaft 19 is hollow over a greater portion of its length to decrease its weight, and is provided with a threaded extension 22 for attachment to an adjacent switch structure arranged in tandem as shown in dash lines, or other appropriate actuating mechanism such as a solenoid.

Associated with the fixed end of the switch is a concentrically disposed tubular conductive member 23, rigid- 1y fixed at one end to the end plate 4 and provided at its other end with a contact surface 24 adapted to make or break contact with the opposing contact surface 17 of the mobile contact. It will thus be apparent that the fixed and mobile contacts provide broad annular surfaces over which radio frequency currents may be conducted, while also providing sufiicient mass to accommodate high direct currents and low frequency alternating currents. This structure also provides a mechanical stability against relative transverse displacement of the fixed and mobile contacts not found in conventional solid conductor switches.

To insure that such relative transverse displacement between the contacts does not occur, and further, to enable axially directed actuating movement of the mobile contact from outside the envelope, the end plate 4 supports an auxiliary actuator shaft 27, slidably journaled in a dielectric bearing 28 detachably mounted as by threads 29 in a central aperture formed in plate 4. An expansible bellow 31 surrounds the actuator shaft 27 and is hermetically sealed at one end to the plate 4 and at its other inner end is hermetically united to a second transverse wall section 32, which is in turn united to the inner end of actuator shaft 27. The transverse Wall section 32 serves to close the inner endof the bellow 31, and forms a base or mounting structure for a dielectric actuator shaft extension 33, which extends rigidly between transverse wall section 32 and transverse wall section 14 associated with the mobile contact 16. From this it will be seen that the bellow and transverse wall section 32 cooperate to form a second reentrant portion of the envelope, and that the switch may be actuated by axial displacement of either of actuator shafts 19 or 27, the latter actuator shaft being provided with a long central bore to lighten the shaft, which is also internally threaded as at 34 to receive the threaded end 22 of the actuator shaft of another switch arranged in tandem as shown in dash lines, or some other appropriate actuating means such as a solenoid.

Where the switch is used as an independent unit instead of being interconnected in tandem with other like switches, the actuator shaft 27 may be used as the actuator means by which the mobile contact is pushedout of contact with the fixed contact. This arrangement places compressive stress on the dielectric shaft extension 33 in opposition to atmospheric pressure which tends to keep the contacts closed. It will of course be apparent that the differential in cross-sectional area of the two reentrant portions of the switch envelope will determine the force exerted by atmospheric pressure in a switch closing direction. Alternatively, the actuator shaft 19 may be provided with a restraining spring (not shown) working between end plate 3 and shaft 19 to overcome atmospheric pressure and maintain the contacts in open position. In such a modified construction the shaft 19 may be used to push the shaft to close the contacts, or the actuator shaft 27 may be used to pull the cont-acts into engagement. It will thus be apparent that the switch structure as herein disclosed lends itself to a number of the contact surfaces 17 and 24, it is desirable to shield the adjacent surface of the ceramic 2 and the dielectric shaft extension 33 against the deposition thereon of vaporized contact metals. For this purpose a tubular metallic shield 36 is disposed concentrically between the annular contacts and the centrally disposed dielectric shaft extension 33. The shield is conveniently provided with a transverse radially extending flange 37 useful to shield the bellow 31 from high velocity particles of contact metal. The flange 37 is formed integral with a cylindrical flange 38 brazed to the tubular fixed contact 23 as shown. A similarly constiuted shield 39 is concentrically disposed between the tubular conductive members 16-23 and the tubular ceramic 2. This shield is also provided with a transverse radially extending flange 4-1 to shield the bellow 13- and a cylindrical flange 4 2 to braze the shield structure to the tubular member 16. It will be seen from this arrangement that vaporized contact metal projected inwardly toward the center of the envelope will be deposited on the adjacent surfaces of shield 36 and on the adjacent surfaces of the tubular contact members 16, 2-3 and transverse wall 14. Very little, if any, vaporized metal will be deposited on the dielectric member 33. It will thus be seen that the shield structure provides relatively cool metallic surfaces in the form of an annular channel on which vaporized contact meta-l may be deposited and condensed without forming a conductive path between opposing contacts. Ordinarily, it is undesirable confine an are too closely within a shield structure for the reason that ionized gases are prevented from dispersing as rapidly as is desirable, thus sustaining the arc. In the present construction, however, the annular contact chamber permits rapid condensation of the vaporized metal and provides sufiicient volume to accommodate the usual amount of arcing without deleterious effect.

I claim:

1. A switch comprising first and second conductive end plates, a dielectric envelope extending between said end plates and hermetically sealed thereto, first and second operating rods slidably journaled in and extending through a respective end plate and axially disposed within the envelope, the internal end of one rod connected to the internal end of the other by dielectric means whereby the operating rods are movable in unison in an axial direction from either extending end, oppositely disposed reentrant portions extending within the envelope from the end plates, surrounding the operating rods and including expansible sections and transverse wall sections axially spaced apart and attached to the internal ends of the operating rods, a first contact means attached to the transverse wall section of the first operating rod for movement therewith, and a second contact means surrounding the reentrant portion of the second operating rod and fixedly attached to the adjacent end plate for engagement by the first contact means, said axially extending operating rods operable from either external end thereof to move the first contact into and out of engagement with the second contact.

2. A switch comprising an hermetically sealed envelope having oppositely disposed reentrant portions including expansible sections and transverse wall sections axially spaced apart and movable in unison in an axial direction within the envelope, a movable contact within the envelope mounted on one of the movable transverse wall sections, a fixed contact within the envelope including a tubular conductive contact support member coaxially disposed about one of said reentrant portions, and contact actuating means journaled on the envelope and connected with the movable contact and operable from either end thereof to move the movable contact into and out of engagement with the fixed contact, dielectric means being provided electrically insulating the transverse Wall sections one from the other when the switch contacts are separated and supporting the movable contact against transverse misalignment in reference to the fixed contact.

3. The switch according to claim 1, in which the first and second contact means include tubular conductive portions and annular contact surfaces.

4. A switch comprising an hermetically sealed envelope having oppositely disposed reentrant portions including expansible sections and transverse wall sections axially spaced apart and movable in unison in an axial direction within the envelope, a movable contact within the envelope mounted onone of the movable transverse wall sections, a fixed contact within the envelope including a tubular conductive contact support member coaxially disposed about one of said reentrant portions, and contact actuating means journaled on the envelope and connected with the movable contact and operable from either end thereof to move the movable contact into and out of engagement with the fixed contact, the contact actuating means including separate actuator shafts having their outer end portions journaled in the envelope adjacent opposite ends thereof and their inner ends fixed to the axially spaced transverse wall sections, and an actuator shaft extension insulatingly interposed between the transverse wall sections in alignment with the separate actuator shafts.

5. A switch comprising an hermetically sealed envelope having oppositely disposed reentrant portions including expansible sections and transverse wall sections axially spaced apart and movable in unison in an axial direction within the envelope, a movable contact within the envelope mounted on one of the movable transverse wall sections, a fixed contact within the envelope including a tubular conductive contact support member coaxially disposed about one of said reentrant portions, and contact actuating means journaled on the envelope and connected With the movable contact and operable from either end thereof to move the movable contact into and out of engagement with the fixed contact, said envelope being symmetrical about a longitudinal axis, the fixed and movable contacts being annular and radially spaced between the axis of the envelope and the wall thereof, first shield means circumscribing the annular contacts in radially spaced relation thereto, and second shield means circumscribed by the annular contacts and with the first shield means defining an annular substantially metal lined contact chamber within which vaporized contact metal is condensed.

6. In an electric switch having fixed and movable contacts mounted within an hermetically sealed envelope, an envelope construction comprising an elongated tubular dielectric portion closed at each opposite end by a metallic end plate united thereto in a manner to accommodate differences in thermal expansion and contraction between the dielectric portion and metallic end plate, a tubular reentrant portion on each end plate concentrically disposed within the tubular dielectric portion adjacent each end thereof and including an expansible section and a transverse w all section, and dielectric means interconnecting the transverse wall sections within the envelope so that movement of one transverse Wall section effects movement of the other, said fixed contact being directly mounted on one end plate and the movable contact being disposed on one of the transverse wall sections for movement therewith into and out of engagement with the fixed contact.

References Cited by the Examiner UNITED STATES PATENTS 3/1962 Jennings 200-144 3,174,019 5/1965 J'ansson 200144 FOREIGN PATENTS 510,93 3 10/ 193 0 Germany. 964,405 7/ 1964 Great Britain. 571,959 1/1958 Italy.

KATHLEEN H. CLAEFY, Primary Examiner. ROBERT K. SCHAEFER, Examiner.

1 E. CRAWFORD, Assistant Examiner. 

4. A SWITCH COMPRISING AN HERMETICALLY SEALED ENVELOPE HAVING OPPOSITELY DISPOSED REENTRANT PORTIONS INCLUDING EXPANSIBLE SECTIONS AND TRANSVERSE WALL SECTIONS AXIALLY SPACED APART AND MOVABLE IN UNISON IN AN AXIAL DIRECTION WITHIN THE ENVELOPE, A MOVABLE CONTACT WITHIN THE ENVELOPE MOUNTED ON ONE OF THE MOVABLE TRANSVERSE WALL SECTIONS, A FIXED CONTACT WITHIN THE ENVELOPE INCLUDING A TUBULAR CONDUCTIVE CONTACT SUPPORT MEMBER COAXIALLY DISPOSED ABOUT ONE OF SAID REENTRANT PORTIONS, AND CONTACT ACTUATING MEANS JOURNALED ON THE ENVELOPE AND CONNECTED WITH THE MOVABLE CONTACT AND OPERABLE FROM EITHER END THEREOF TO MOVE THE MOVABLE CONTACT INTO AND OUT OF ENGAGEMENT WIH THE FIXED CONTACT, THE CONTACT ACTUATING MEANS INCLUDING SEPARATE ACTUATOR SHAFTS HAVING THEIR OUTER END PORTIONS JOURNALED IN THE ENVELOPE ADJACENT OPPOSITE ENDS THEREOF AND THEIR INNER ENDS FIXED TO THE AXIALLY SPACED TRANSVERSE WALL SECTIONS, AND AN ACTUATOR SHAFT EXTENSION INSULATINGLY INTERPOSED BETWEEN THE TRANSVERSE WALL SECTIONS IN ALIGNMENT WITH THE SEPARATE ACTUATOR SHAFTS. 